Spatio-Temporal Features of Visual Exploration in Unilaterally Brain-Damaged Subjects with or without Neglect: Results from a Touchscreen Test

Abstract

Cognitive assessment in a clinical setting is generally made by pencil-and-paper tests, while computer-based tests enable the measurement and the extraction of additional performance indexes. Previous studies have demonstrated that in a research context exploration deficits occur also in patients without evidence of unilateral neglect at pencil-and-paper tests. The objective of this study is to apply a touchscreen-based cancellation test, feasible also in a clinical context, to large groups of control subjects and unilaterally brain-damaged patients, with and without unilateral spatial neglect (USN), in order to assess disturbances of the exploratory skills. A computerized cancellation test on a touchscreen interface was used for assessing the performance of 119 neurologically unimpaired control subjects and 193 patients with unilateral right or left hemispheric brain damage, either with or without USN. A set of performance indexes were defined including Latency, Proximity, Crossings and their spatial lateral gradients, and Preferred Search Direction. Classic outcome scores were computed as well. Results show statistically significant differences among groups (assumed p<0.05). Right-brain-damaged patients with USN were significantly slower (median latency per detected item was 1.18 s) and less efficient (about 13 search-path crossings) in the search than controls (median latency 0.64 s; about 3 crossings). Their preferred search direction (53.6% downward, 36.7% leftward) was different from the one in control patients (88.2% downward, 2.1% leftward). Right-brain-damaged patients without USN showed a significantly abnormal behavior (median latency 0.84 s, about 5 crossings, 83.3% downward and 9.1% leftward direction) situated half way between controls and right-brain-damaged patients with USN. Left-brain-damaged patients without USN were significantly slower and less efficient than controls (latency 1.19 s, about 7 crossings), preserving a normal preferred search direction (93.7% downward). Therefore, the proposed touchscreen-based assessment had evidenced disorders in spatial exploration also in patients without clinically diagnosed USN.

Hemispatial Neglect: Computer-Based Testing Allows More Sensitive Quantification of Attentional Disorders and Recovery and Might Lead to Better Evaluation of Rehabilitation

“…Stimuli may be presented in varying locations and times across trials, sessions, and sensory modalities, and repeated many times (Deouell et al, 2005; Bonato et al, 2010; Buxbaum et al, 2012; Van Vleet and Degutis, 2013). Various difficulty levels can be easily implemented and eventually combined with concurrent tasks to manipulate the load, and may be combined with other measures (e.g., eye movements, Van der Stigchel and Nijboer, 2010; touch screen recording, Rabuffetti et al, 2012). These features, along with the addition of RT measures, reduce the chances for ceiling effects and allow for quantitative, continuous measures, and even significance levels in single patients, including sensitive individual monitoring of performance changes through repeated assessments.…”

Self-rehabilitation of acquired brain injury patients including neglect and attention deficit disorder with a tablet game in a clinical setting

“…This spatial measure allowed for both lateral and near-far (targets towards the bottom are closer than those on the top) neglect discrimination. Rabufetti found that the temporal measure of inter-cancellation times -the time between one and the following cancellation -was higher for patients than for controls [33], which translated well into the game time divided by the number of targets hit in WAM. In an earlier study [22], we found that empirical parameters from Fitts' law (a, b) from modelling rapid touch interactions in games can help predict neglect.…”

“…EBP * Corresponding author. Email: hk@create.aau.dk requires digital versions of standard tests based on paper and pencil [11,33], which are slow, expensive to administer (Jehkonen et al 1998), and less precise. Additionally, digital tests can record valuable temporal data to improve diagnostics and monitoring of chronic patients.…”

Towards a Dynamic Assessment of Unilateral Spatial Neglect

“…No time limit was imposed and the participants were assessed to the limit of their possibilities. However, according to the rules suggested by Rabuffetti et al [18], if a participant had not declared the test conclusion after 10 minutes, he/she was asked whether the test was finished or not.…”

“…Rabuffetti, Farina, Alberoni, Pellegatta, Appollonio, Affanni, et al [18] implemented a computerized cancellation test adopting a touch screen interface. Stimuli were letters or shapes.…”